Apparatus for continuous recovery of magnesium



3 Sheets-Sheet l ATTORNEYS April 14, 1953 F. J. HANSGIRG APPARATUS FOR CONTINUOUS RECOVERY OF MAGNESIUM Original Filed June 26, 1945 A fl v 5 4. v z w z a fl w W 6 I M W? 2 a j //,//////.//7//, a a w y Y J m j m Q 4 n fi ml hhhn .u x a "U" n W a a I INVENTOR 9 ATTORNEYS 3 Sheets-Sheet 2 April 14, 1953 F. J. HANSGIRG APPARATUS FOR CONTINUOUS RECOVERY OF MAGNESIUM Original Filed June 2 1945 4 n f V fllfflllllllillillll A ril 14, 1953 F. J. HANSGIRG 2,634,959

I APPARATUS FOR CONTINUOUS RECOVERY OF MAGNESIUM Fatented Apr. 14, 1953 UNITED STATES PATENT OFFICE APPARATUS FOR CONTINUOUS RECOVERY OF MAGNESIUM Original application June 26, 1945, Serial No. 601,701. Divided and this application April 24, 1950, Serial No. 157,736

12. Claims.

This invention relates to the production of metallic magnesium, and has for its general object the provision of novel apparatus for producingmagnesium by a substantially continuous process. This application isa division of copending application Serial No. 601,701, filed June 26, 1945, which matured as United States Patent 2,570,232 on October 9, 1951.

In thermal reduction processes, as pursued at the present time, either by reduction of raw material containing magnesium'oxide by means of calcium carbide, ierro-silicon, silicon carbide, or similar reducing agents, or in the distillation of magnesium dust which has been recovered by a thermal reduction process, batch methods are employed. In all of these processes, the problem involves heatin the starting materials to temperatures of between l000 and 1300 C. in a high vacuum; and in the case of the recovery of magnesium from dust produced by the thermal reduction method, tempertaures of from 600 to 750 C. are necessary, while also maintaining high vacuum conditions. The necessity for introducing the raw materials into high vacuum and the fact that magnesium at its melting point already has a vapor pressure of 2.5 mm. of mercury (absolute pressure), makes it exceedingly difficult to provide a continuous process. Several proposals have been made looking toward the solution of the problem of continuous distillation, but the difficulties in providing suitable apparatus have been considered insuperable and the simpler arrangements for batch processes have been considered more economical and practical.

It is therefore one of the principal aims of the present invention to provide means for carrying on the thermal reduction of magnesium compounds in a substantially continuous, or semicontinuous way. That is to say, the apparatus in which the process is carried on does not have to be opened to the atmosphere for the introduction of the starting materials nor for the removal of the magnesium produced or the waste material, the introduction and withdrawal of the materials and their transfer from one stage to theother being preferably automatically effected according to a time cycle adjusted for the specific raw materials and reducing agents employed.

In all of the above mentioned reduction processes, a vacuum of at least 1 mm. to 0.1 mm. of mercury (absolute pressure) is necessary. It is therefore essential that the magnesium be condensed in the solid state since only solid magnesium has a vapor pressure below the degree of vacuum mentioned.

It has previously been proposed, in the distillation of magnesium dust produced by carbothermal reduction methods, to tablet the dust and to use the tablets as resistors through which an electric current may be passed. The magneslum vapors are then withdrawn from the mass of tablets through openings or slits in the heating chamber and thence to be conducted to exteriorly arranged condensing chambers which are maintained at temperatures proper for the condensation of the magnesium in liquid form. Such arrangements turned out to be quite impractical since the condensation of magnesium in the liquid state is attended by great difficulties. Also such procedure is only applicable to the distillation of metallic magnesium which has already been previously extracted and which can be evaporated at much lower vacuums, say between 10 and 20 mm. absolute pressure, so that liquid condensation is actually possible to some extent. But, of course, such processes become inoperative when a higher vacuum is necessary in carrying out the reduction process, as for example with reducing agents such as calcium carbide, ferrosilicon, silicon carbide, or aluminum alloys. Also, it may be mentioned that the method of usin tablets as resistors to which reference has been made, is attended with great diificulties, since in the larger types of equipment, irregular heat distribution takes place, and since all of these materials have a temperature coefficient of resistivity which reduces with an increase in temperature, the current concentrates on such zones of lower resistance which therefore increase in temperature so that any such preferred path for the current gives rise to very irregular heat distribution.

It is also impractical to introduce any considerable amount of tablets directly from the open air into high vacuum equipment since these tablets are all of a porous nature and contain occluded gases which would be liberated as they entered a high evacuated evaporation or reduction zone, and the vacuum would lower to such a degree that the reduction would stop. The continuous introduction of fresh material into any process of this type would involve the utilization of very large and powerful vacuum pumps.

In order to overcome the difhculties attending the introduction of raw materials, whether tableted or not, into a high vacuum chamber, the present invention contemplates introducing the materials first into a preheating chamber in which they are heated to such a temperature, under moderate vacuum conditions, that no actual reduction or evaporation of magnesium takes place but all occluded gases are liberated from the raw materials to be reacted or treated. It is desirable that such preheating take place at a temperature at which the formation of magnesium vapors would just begin, or at which magnesiumalready previously produced would start to evaporate. The vacuum applied is also only slightly diiferent from the vacuum applied later for the actual reduction or distillation. The temperature and vacuum conditions applied according to the invention will vary somewhat with the reducing agent and raw material employed, but in the specific example described, certain exemplary temperatures and pressures will be mentioned in connection with the reducing agent calcium carbide and ferro-silicon. Suitable temperature and pressure conditions will also be suggested in connection with the distillation of magnesium dust,

A further and more specific object of the invention is to provide apparatus for the substantially continuous production of magnesium in which the pretreated materials are directly charged through a lock chamber system from the pretreatment zone to the reduction or evaporation chamber.

Again, in equipment at present in use for the thermal reduction of magnesium with calcium carbide, ferro-silicon and similar materials, evaporation takes place from retorts which are externally heated. The same holds true for the distillation of magnesium dust resulting from a thermal reduction process. In all such arrangements in which steel retorts are employed, a very high heat resistant steel must be used in order to withstand the vacuumat high temperatures. The disadvantage of retorts generally, resides in the fact that the magnesium vapors evolved from the reaction products have to pass through the whole charge before they enter the condensation chamber. To eliminate this disadvantage the applicant has already proposed, in his United States Patents Nos. 2,309,647, 2,309,64 and 2,310,188, to insert within the retort a system of shutters similar to Venetian blinds, through which the magnesium vaporscan be withdrawn to a central cylindrical open space, Without havin to pass through the mass of raw material charged into the retort. According to the system forming the subject of the present invention, no exteriorly heated retort is used, and furthermore the method of using the tableted starting material as a resistor forthe electric current, is generally avoided or applied to such a degree that the flow of the current is Well controlled. In accomplishing this object, the invention contemplates the provision of retorts in which the retort wall itself comprises the resistant conductor for the passage of the electric current. Metal retorts, made of certain heat resistantsteels, could possibly be employed but even the best heat resisting alloys at the high temperatures used may become quite soft so that the structure might deform or even collapse. Therefore, it is preferred that there be used for the retort walls, materials of high electric resistance and high melting points, for example carbon, graphite, or silicon carbide. Alternative forms of these heating chambers will be specifically described in the present specification and it is understood that the upper and lower portions of the retort walls are connected respectively with the current supply so that the retort between these points is highly heated and the material to be reacted moves downwardly by gravity within the heating chamher.

A further object of the invention isithe provision of a system of automaticcontrols whereby successive charges of materials may be passed through the pretreating and final heating zones with suitable simultaneous adjustments of valves, feeding means, vacuum and pressure controls, etc,

Other objects and features of novelty will be apparent from .the following specification when readin connection with the accompanying drawings in which certain embodiments of the invention-are illustrated by way of example.

In the drawings:

Figs, 1A and 1B show vertically aligned portions of one form .of apparatus which may be employed in pursuing the invention, thedisclosure being somewhat schematic with conventional parts and devices being indicated diagrammatically, and the structure being for the most part shown in vertical section;

Fig. 2 is a fragmentary enlarged view :in side elevation of one form of heating, reducing, or evaporating retort;

Figs. 3, l, and 5 are views infragmentaryelevation, vertical section, and horizontal section, of an alternative form of retort which may be used in substitution for the one illustrated in Figs. 1B and2 of the drawings; and

Figs. 6, 7. and 8 are diagrams of the automatic controls which are adapted "to be actuated by the passage of the material past points at the inlet and discharge portions .of the apparatus-and also at an intermediate transfer point,'where-the.material passes from the pretreatment chamber to the retort.

Referring particularly to Figs. 1A and 1B of the drawings, it will be seen that the pretreatment portion of the apparatus designated A is adapted to be superposed upon the retort :portion B, and above the pretreating section .A a lock chamber charging section C is disposed. Between the pretreatment section A and the retort section B there is disposed .a discharge chamber D which introduces the pretreated material into a lock hopper arrangement E. Finally, the waste material from the retort B leaves the apparatus through a discharge section F.

The charging arrangement C comprises a bin or hopper il into which the raw materials, in-- cluding the magnesium containing compounds and the reacting materials, are adapted to be placed. For example, in the reduction of .a magnesium silicate with calcium carbide, a prereduced magnesium silicate ore is mixed with the stoichiometric amount of calcium carbide and pressed into tablets which are charged into the bin or hopper H. The material may be fed into the lock chamber I2 by opening the valve l3. discharge the material from the lock chamber 12 into the pretreatment chamber I5 which com prises an elongated vertical cylindrical chamber passing centrally through the pretreatment installation A. The lock chamber l2 may be periodically subjected to vacuum from the line [1, a valve I8 controlling the connection of the line i! with the vacuum line 19 leading to the vacuum pump 20. The line 19 connects directly with the pretreatment chamber l5.

Surrounding the pretreatment chamber I5 is the insulated casing 22 having an annular internal heating chamber 23 in which are disposed an annular series of vertical resistor rods '24.

Another valve it may be opened to Conductor rings 25 are disposed at the upper and lower ends respectively of these rods and these rings are connected to a suitable source of heating current by means of the lines 26. The resistors and the source of current are of such a nature that a temperature of between 900 and 950 C. may be maintained in the heating chamher.

The lower end of the pretreatment chamber I5 extends beyond the furnace 22, 23 and is surrounded by a cooling water jacket 30 which is supplied by the pipes 3i and 32. It may become necessary to cool the charge by means of this water jacket before it enters the hopper connecting the pretreatment chamber I5 with the other portions of the apparatus.

From the pretreatment chamber I5 the material passes into the discharge device D which consists of a hopper 33 in which a rotating disk 34 is carried upon the end of a shaft 35 adapted to be driven by the motor 36 through the bevel gears 31. A scraper element 38 cooperates with the disk 34 and may be adjusted to control the discharge of material from the disk 34.

From the hopper '33 the pretreated material is passed through the valve 40 into a lock or charging chamber 42, and from thence through the valve 43 into a charging chute 44 which is introduced into the retort 45 within the retort furnace B. By operating the valves 40 and 43, the lock chamber 62 may be alternately placed in communication with the vacuum system of the pretreatment chamber I5 or that of the reducing or distilling retort 45. The vacuum in the reduction retort system B is maintained through a line 41 which leads to the high vacuum pump 5%]. The other connections from this pump will be later described.

The retort chamber comprises the elongated cylindrical tube 45 which in this embodiment consists of a tube of carbon provided with a spiral slit 52 through which the magnesium vapors may pass into the surrounding chamber 55, the chamber 55 being lined with blocks or stones of carbon indicated at 56. Adjacent the upper end of the retort tube 45 is the annular water cooled contact ring 58, and a similar ring 59 is secured to the lower portion of the tube, both of these rings being connected with a suitable source of current by the leads 60 and 6| Within the upper portion of the retort casing B and surrounding the upper portion of the retort tube 45 is the annular condensing chamber 65, this chamber being provided with an inlet passageway 66 for magnesium vapors and a trough or gutter 61 for cooling the condensed magnesium. A conical flange 68 cooperates with the vertical flange 69 to provide a narrow circular gas passageway Iii for admitting the vapors to the condensing chamber 65. An inclined discharge duct I2 leads from the trough 61 and this passageway is provided with a refractory or carbon plug I3 and a cover or closure 14 both of which are adapted to be removed when the magnesium is periodically tapped from the trough 61.

- The condensing chamber 65 is provided with a jacket 15 through which an air or gas stream can be circulated, this stream entering through the line I6 and leaving through the line 11, these lines being respectively controlled by valves 18 and I9.

Heating means are provided for the condensing chamber 65 within the outer annular casing 80, this heating means comprising an annular series of resistor rods 8I having rings 82" 'at the upper and lower ends, which rings are connected with a source of current by the leads 83.

All of these chambers and retort passageways are enclosed within the insulation 85 which is in turn covered by the shell or outer wall 66 which houses the entire retort system B.

A tubular lower extension extends from the lower end of the retort tube 45 exteriorly of the casing 86, and waste material-is discharged from the retort through this extension into the dis charge mechanism F which consists of the discharge hopper 9| in which a rotating disk 92 is provided similar to the disk 34 described in connection with the hopper 33 in the discharge arrangement D. A scraper 93 is associated with the disk and a motor 95 serves to rotate the disk through the gearing 96 and the shaft 91. The motor 95 is of the variable speed type by means of which the rate of discharge of the waste into the bin 98 may be controlled. The waste material may be periodically discharged from the bin 98 through the valve 99. i

As already indicated the vacuum line 41 leads from the condensing chamber 65 which is also in communication with the interior of the retort 45 and the surrounding chamber 55. The pipe 41 may be placed in communication with the high vacuum pump 50 by means of thevalve I00. The line may also be placed in communication with a source of supply ofa gas which is inert to magnesium, by means of the valve MI and the pipe line I02. Such gas may be hydro-' gen or one of the inert gases, argon, helium, or the like. A valve I04 in the line I65 serves to connect the intermediate lock chamber 42 with the vacuum pump 50.

A connection I36 is provided in the tube 44 which introduces the material into the retort 45, and a similar connection IIJI communicates with the discharge portion 90 leading from the retort 45. A small quantity of an inert gas can be introduced through these lines during the operation to prevent any condensation of magnesium vapors in the zones where the raw material is charged and the waste withdrawn.

In Figs. 3, 4, and 5 of the drawings there is illustrated an alternative form of retort which may be substituted for the tube 45. In this embodiment the walls of the retort consist of an annular series of vertically disposed rods IIU, these rods being made of carbon, graphite, silicon carbide or other resistant material. Narrow spaces I I I are left between the rods through which the magnesium vapors may escape, All of the rods Ilfl are socketed as at H2 in the upper and lower annular rings I I3 and I I4, which rings are connected with a source of current by means of the conductors H5 and H6.

Of course the retort chamber may be varied still further, the rods I It! being arranged in either a circular form or in helical or rectangular configuration. The slits between the rods are of course small enough to retain the tablets and prevent their falling out into the surrounding chamber 55.

The surrounding insulating material 85 is selected so as to provide a jacket which is not too porous. The whole arrangement is placed within the jacket 86 which can be maintained at a temperature of approximately 500 C., and if desired an outer jacket of porous or non-porous insulating material may be provided as suggested at 85' in Fig. 1B.

In cases where magnesium containing materials like powdered magnesium oxide or magneassesses silicate ores are to be reduced with calcium carbide, the pretreatment zone within the cham-' ber I has to be maintained at temperatures around 900 1to 950 C. and at a vacuum of from about 1 to 2 mm. of mercury absolute pressure. It is of course also possible to use a vacuum of between from 1 to mm. Under a vacuum of 1 mm. there may be some magnesium losses in the pretreatment stage, and on the other hand a vacuum of 10 mm. may not lead to a=satisfac-- torily thorough degassing of the raw materials. For mixtures of dolomite with ferro-silicon, a pretreatment temperature-of from about 1050 to 1100 C. anda vaccum of between 1 mm. and 3 mm. pressure is of advantage.

The magnesium vapors condense on the surface of the chamber 65 in solid form usually at a temperature range of 490 and 600 C.

The operation of the installation may be effected entirely automatically or by manual control. In the latter case the raw materials and reducing agents in pellet form may be placed in the charging bin H. Then with the charging valve I4 closed, the valve 18 closed so as to cut off the vacuum from the lock chamber i2, and the valve l-8A opening the chamber to the atmosphere, the material valve 13 is opened and the lock 12 filled. Then the valve i3 is closed, the valve 18A is closed, and the valve it opened to vacuum. The valve 14 may then be opened and the material discharged into the pretreatment chamber &5. In the pretreatment chamber the material is heated by passing through the zone which is surrounded by the furnace 23, 24.

When the material from the 'pretreating installation A is to be transferred to the retort installationB, the material valve 43, the gas valve WI, and vacuum valves its and tilt are closed, the valve it is opened and the motor starts the discharge mechanismt l operating. 'The pretreated material is charged into the lock chamber or bin 32 and then the motor 36 is stopped, the valve 49 closed, the vacuum valves I66 and it :opened and then after operation vacuum has been reached the valve #33 is opened so that the material can be charged into the reaction chamber 45.

When sufiicient material has been charged into the retort tube 45 it is heated to the reaction temperatureapproximately between 900 and 950C. by means of current supplied through the leads 69 and 61 to the conductor rings 58 and 59 at opposite ends of the resistant retort tube 65. During the reduction or volatilization of a charge, cooling air is admitted through the valve 1'8 to the jacket 55 and exhausted through the outlet valve 79. This keeps the condensation chamber 65 at the proper temperature to cause the vaporized magnesium to condense on the walls. At the same time valve use is maintained open and the high vacuum pump 53 reduces the pressure'within the reaction chamber to the desired degree.

After the deposit in the condensing chamber 65 has reached a predetermined thickness, the flow of material in the reduction chamber is stopped, vacuum valves it!) and lot are closed, and the vacuum :in the portion .of the system including the charging :bin or look 42, the reaction chamber 45, the discharge hopper 9i, and the Waste bin 98 is released by opening the valve 1M, thus admitting a quantity of inert gas. The air cooling of the condensing chamber 85 is stopped by shutting on the valves 18 and 19 and thexcurrentsupplied through the leads :83 to the.

heater 8! is "turned on so that the'con'densing chamber is raised 'toa temperature at which the magnesium melts down from the walls and runs into the gutter 6?, that portion of the magnesium which has adhered to the inner wall of the chamber being guided into the gutter by means of the conical eaves .558. To discharge the molten magnesium the cover 74 is removed from the outlet tube 12 and the inserted carbon rod or plug 73 is withdrawn and the magnesium tapped from the opening in liquid form. At the same time the waste material may be withdrawn from the chamber 98 through the valve 29. After this, the rod '73 is :re-introduced into the discharge pipe .12, the vacuum-tight cover it is closed and the system placed under vacuum again by opening valves Hit and um (of course, after closing gas valve mi). reached, the discharge mechanism $2 is turned on again to continue the operation.

In carrying out the process in a substantially automatic way, the opening and closing of the valves and the connection and disconnection of the vacuum pumps can be effected by remote control electrical or electronic devices or robots. It can easily be determined by experiment how much magnesium a certain volume of tablets will produce when a certain raw material m'mture is used. This ratio gives therelationship between the volume accumulating in the waste chamber 93 and the volume of magnesium accumulating in the condensing chamber 55. A level controlled device lii'i is arranged in the upper portion of the waste receiving chamber Qikata point where the waste representing one charging of material will reach. When the waste material discharged by the rotating disk mechanism 92 reaches the level of "the element till, controlling mechanism in the frobot itilis actuated. This mechanism is preferably electrical and the level indicator or level res onsive elemen so! may comprise any sort of s tching device which will be actuated by the rising level of pulverulent waste material. The devices disclosed in United .States Patents 1,578,563, 1,951,980'and 1,977,228 are only a few examples of devices of this kind which maybe utilized.

Referring now to Figure 8 of the drawings,

it will be seen that the switching mechanism in the robot etc will serve to actuate the controlling motors 3H, M2, M3, etc. to control the several valves and motors as will .now be described. The actuating or controlling .motorsi 41 l, iii, 313, etc. are connected with the master controlling device .or robot its by means of the pairs of conductors 329, and upon actuation of the levelresponsive clement i-iii, current is supplied to the motor All which is connected with the material introducing valve 33 as by means of the shaft 32i to turn this valve off if it is on, and to keep it turned off if it has already been turned off by other controls. Similarly the motor 312 acts through a corresponding shaft 42! to turn'the vacuum valve itiinff. The motor M3 is actuated to turn the vacuum valve tee off which will disconnect the lock ti. from the vacuum pump 5t. Motor tit turns the valve liil on, thus admitting inert gas to the retort and condensing system. This same actuation of the level re sponsive member is: tru'ns the motor off and stops the delivery mechanism 32. Similarly the motor 4 It serves to turn the cooling air admitting valve 58 oli and at the same time the heating elementssupplied through the leads 83 are turned on to start the-melting of the deposited magnesium.

After .full vacuum has been The time necessary to. melt down the magnesium can be easily determined experimentally, and the timing mechanism 4| 1 can be adjusted so as to give a signal such as a visual signal aiiorded by the light 418' which when observed by the operator will indicate to him that it is time to remove the cover 74 and the plug 13 and tap the magnesium, and also to open the discharge valve 99 to empty the container 98.

In order to keep the charging bin 42 independently filled with pretreated raw materials a second controlling device or robot 3% is provided. This controller has one section SMA adapted to be energized by a high level responsive element SM and another section 30633 to be energized by the low level control device 392. These elements 30! and 3li2Jare connected respectively to the control devices by the conductors 3&3 and 3%. When the material discharged into the retort through the valve 43 reaches the low level 3622,

the device 3W3 is energized to close the valves 43 and 104, open the valve All and start the motor 38 for operating the discharge mechanism '34.

- Then the pretreated raw material is charged into the hopper or lock chamber 42 until the level 3 3! is reached. At this point the high level control portion 300A of the mechanism 35H is energized to close the valve 49, shut oh the delivery motor 36, and if the lowermost system of controls centered about robot 469 permits it, open the valves 43 and HM. It will be noted that in the conductor line 320 leading to the motor 3l2 which controls the valve 43 there is disposed a vacuum gage which delays the energizing of the motor 3 i2 until operation vacuum has been reached. The several valves and discharge mechanisms are adapted to be actuated by the indicated motors 3i i, 312, 3 i3, etc, through the shafts 32 I.

In a similar fashion, a third electrical or electronic controller 200 is employed to control the initial charging mechanism C. This device comprises a high level control portion 208A adapted to be activated through the conductor 203 from the high level responsive element 29! and a low level control portion 290B energized by the low level responsive element 282. When the low level responsive element 282 is actuated, the control 2083 is energized to actuate the appropriate motors to open the valve [3, to close the valve M, to close the vacuum valve [8, and to open the vvalve IBA venting the chamber I2 to the atmosf phere.

After the lock chamber l2 hasbeen filled to the level 261 the high level control 258A is en "ergized' to turn the valve i 3 oil, to turn the valve I ton, to, turn the vacuum valve l8 on, and to close the valve 18A leading to theatmosphere.

The operation of valve [4 is dependent upon the attainment of the necessary operating vacuum,

and for this purpose the vacuum gage 205 is interposed in the line 220 leading to the motor 2 [2 which actuates this valve.

Thus it will be seen that with such automatically controlled devices. it is possible t maintain the correct operation of this installation with ters Patent is:

1. An installation for the continuous recovery of metallic magnesium adapted 1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents which will not evolve gaseous products and (2) for the evaporation of magnesiiun contained in the dust produced by other thermal reduction methods; said installation comprising, in combination,'a vertically arranged, gravity-feed;intercommunicating series of airtight, storage, heating, transferring, and discharge chambers, selectively operable valves con;- trolling communication between adjacent chainbersor" the series and between the respective top and bottom end chambers'and the atmosphere, one of said h ating chambers being a prelimi-- nary treatment chamber and a subsequent heating chamberbeing a retort chamber adapted to be subjected to :liigh temperature and vacuum in order to evolve the magnesium vapors from the pretreated material, means for selectively evacuating said respective heating chambers, gas locks separating the heating chambers whereby material may be passed from one to the other with out loss of vacuum, means for independently applying heat to said heating chambers, automatically actuated means for appropriately controlling said vacuum applying means, and material level responsive devices in certain of the chambers for actuating said controlling means.

2. An installation for the continuous recovery of metallic magnesium adapted (1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents which will not evolve gaseous products and (2) for the evaporation of magnesium contained in th dust produced by other thermal reduction methods; said installation comprising, in combination, a vertically arranged,

gravity-feed, intercommunicatin series of airtight,-storage, heating, transferring, and discharge chambers, selectively operable valves controlling flow of material between adjacent chambers of the series and between the respective top and bottom end chambers and the exterior of the installation, one of said heating chambers being a preliminary treatment chamber and a subsequent heating chamber being a retort chamber adapted to be subjected to high temperature and vacuum in order to evolve the magnesium vapors from the pretreated material, means for selectively evacuating said respective heating chambers, gas

locks separating the heating chambers whereby material may be passed from one to the other without loss ofvacuum, means for independently applying heat to said heating chambers, means for introducing inert gas into the retort chamber andthe transfer and discharge chambers adjacent thereto only, automatically actuated means for appropriately controlling said vacuum and inert gas applying means and said material valves, and material level responsive devices in certain of the chambers for actuating said controlling means for effecting automatically the treatment and transfer of successive charges of material through the installation.

3. An installation for the continuous recovery of metallic magnesium adapted 1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents which will not evolve gaseous products and (2) for the evaporation of magnesium contained in the dust produced by other thermal reduction methods; said installation comprising, in combination, a vertically arranged, gravity-feed, intercommunicating series of airtight, storage, heating, transferring, and dis- :11 -charge chambers, selectively operable valves controlling communication between adjacent cham- 1 bers .of the :series" and between N the" respective top and bottomi end chambersand the atmosphere,

"OIiBJOf said heatingchambers being a preliminary 1' treatment chamber and :a subsequent heating chamber being ":a retort 'chamber adapted" to be subjected to high =temperature and vacuum in order :to evolve themagnesium vapors 1 from the pretreated material, means for selectively-evacuatingsaid respective heating ohambers, gas locks separating the heating' chambers 1 whereby material -may be passed from the to 1 the other Without-loss of vacuum,means for applying heat to said. pretreatment chamber, insulating :contain- 1 ing walls for sai'd i heating chambers, a retort in said iiretort chamber, the wall -of theretort itself-being:ofelectrically resistant materia1 which is heatedby the passage of "electric current therethrough, means iorapplying electric current to said 1 retort whereby the fi pretreated materialis heated: to the point 'where 'magnesium' vapor" is evolved; a-magnesiu'm condensing cham'ber also enclosed within'the wallsof said retort chamber,

--a:vapor passageway from said -retort' to 'said' cond'ensing chamber, a discharge opening "tor -the --condense'd magnesium leading from said condensing chamber" through the insulating walls of saidretortrchamber; andmeans 'for tightly clos- --ingl said discharge means during 'the distilla'tion "and condensation operation "of :saiddnstallation, automatically zactuated' m'eans 'for appro'priately controlling said vacuum "applying means, and --materjial iev'elresponsivedevices in certain 'df'the -chambers for'actuating"said controlling means.

64. 3111 an apparatus of the olass described, a retort chamber a tubular retort -disposed in said chamber-with' its walls spaeed irom-the walls-of i the i chamber, -m'eans for charging material into and-discharging itfrom' -saidretort, said 'retort beingin the iOr-m of asubstantiallycylindrical cage andcomprisinga completely annular series "of parallel vertical rods,said rods -being of electrica liy resistant material and being spaced'apart a slight-distance to provide openings through 'which said raw material *may not pass but through 'which vaporsevolved from the -material may pass to the 'spacebetween the walls-ofsaid chamber and said'retort, annularrings oi elec- 1 tricall'y conducting material' atthe topa-nd bottom-or said" retort "and connected to the respectiveends of said rods, and conductors "secured to-said' rings and leading to a sourceof eleotric 'currem.

=5. installation "for 'the ccntiriuo'us'recovery *or metallic magnesium adapted ('1) for "the "thermal reduction method involving "reacting magnesium containingcompounds together with reducing agents which --w111 not-evolve-gase'ous products and (2) for theevaporation' of magnesium' contained in the 'dust producedby other thermal reduction methods; said installation comprising, in combinationja vertically" arranged, gravity-feed, interco'mmunicating series of airtightystorage, heating, transferring, and dis charge chambers,selectively operable valves controlling fiow of material between-adjacent chambei's of the series and between the respective "top and bottom' end chambers =-a'nd the exterior of the installation, one of --'said heating chambers *be'inga preliminary treatment Fchamber and' a subsequent heatingchainber beingfa retortachamher adapted to be: subjected to high temperature .and' vacuum in- I order to evolve the magnesium vapors irom the pretreated-Tinaterial, egas -flocks I2 separating-the heating-chambers whereby'material may bepassedirom one to the otherzwithout; loss of vacuum -mean-s for: applying 7 heat to said pretreatment chamber, means' for applying vacuum to said pretreatment chamber, a retort in said-retort chamber, a condensing chamber also in said retort'cchamber, a continuously open vapor passage from said retort to said condensing chamber, means for heating said retort, and means for evacuatingsaid retort chamber includingiboth the retort and the-"condensing--.chamber enclosed therein, a tappingopening inrsaid condensing chambercfor I removal of condensed magnesium,: a :removable air-tight closure for said opening, "means for alternatively providing cooling and heating means to said condensing chamber-to 'jalternatelycondense rand 'remelt the magnesium entering the "chamber from said retort, automatically actuated-means for appropriately controllingsaidvacuum applying means 'to therespective heating chambers, the cooling 'and heat ing means for the condensing chamber and the respective materialfiow valves, andmaterial level responsive devices incertain oi the'storage, transfer, and discharge chambers for actuating said controlling means.

"6.-"Aniinsta1lation for the continuous recovery of metallic "magnesium "adapted (1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents Whichwiil not evolve gaseous :productsand (2) for the evaporation or magnesium contained in the dustproduced by other thermal ':reduction methods; said installation comprising, in'combination, a verticaliyarranged, gravity-feed, intercommunicating series of airtight chambers, said chambersincluding a "pretreatment chamber andaisubs'equent lowerretort chamber, a 4 supply chamber above said pretreat- "chamber to said pretreatment ohambergmeans for applyingand releasing vacuum in "said pretreatment chamber, valve means controlling-the ilow 'ofmaterial into and out of said-transfer chamber, means *for applying and releasing vacuum insaid'retort chamber, material-level ire'sponsivemeans in said transfer chamber for controlling certain of the material valves 'and vacuum supplying and releasing 1 means, and

-meanslfor heatin'g said retort chamber.

I "7. An installation for. the continuous recovery of metallic magnesium adapted (l) ior'the' ther- -ma1' reductionmethod involving reacting: magnesium containing compounds together with reducingagents which" will not evolve gaseous prod-- ucts and (2) I for the'eva'poration of magnesium contained in'thedust'produced by other thermal reduction methods; said installation comprising,

in combination, a vertically arranged, gravityfee'd, aintercoi'nmuni'cating series "of airetight 1 chambers, said chambers including a pretreatment chamber and a subsequent lower :retort chamber, -a supply chamber above" said'pretreat- Y mentchamber and a transfer chamber in the vertical series between the pretreatmentichamber andthe retort chamber, valve means controlling the flow of material from said supply-chamber to .said-'pretreatment chamber,=-means "for applying and releasing vacuum in said :pretreatme'nt chamber, valve means controllingthe tfiow-of material-intoand out of said I transfer chamber, means for applying and releasing vacuum in'said retort chamber, means for heating said retort chamber, material-level responsive means in said supply chamber for controlling certain of the material valves and vacuum supplying and releasing means, and material-level responsive means in said transfer chamber for controlling certain of the material valves and vacuum supplying and releasing means.

8. An installation for the continuous recovery of metallic magnesium adapted 1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents which will not evolve gaseous products and (2) for the evaporation of mag nesium contained in the dust produced by other thermal reduction methods; said installation comprising, in combination, a vertically arranged, ravity-feed, intercommunicating series of airtight chambers, said chambers including a pretreatment chamber and a subsequent lower retortchamber, a supply chamber above said. pretreatment chamber and a transfer chamber in the vertical series between the pretreatment chamber and the retort chamber, valve means controlling the flow of material from said sup ply chamber to said pretreatment chamber, means for applying and releasing vacuum in said pretreatment chamber, discharge regulating means aifecting the flow of material from said pretreament chamber to said transfer chamber, valve means controlling the flow of material into and out of said transfer chamber, means for applying and releasing vacuum in said retort chamber, means for heating said retort chamber, discharge regulating means affecting the flow of residual material from said retort chamber to said discharge chamber, material level respon- Sive means in said transfer chamber for controlling certain of the material valves and vacuum supplying and releasing means and said discharge regulating means.

9. An installation for the continuous recovery of metallic magnesium adapted (1) for the thermal reduction method invloving reacting magnesium containin compounds together with reducin agents which will not evolve gaseous roducts and (2) for the evaporation of magnesium contained in the dust produced by other thermal reduction methods; said installation comprising, in combination, a vertically arranged, gravity-feed, intercommunicating series of airtight chambers, said chambers including a pre treatment chamber and a subsequent lower retort chamber, a supply chamber above said pre treatment chamber and a transfer chamber in the vertical series between the pretreatment chamber and the retort chamber, and a residue discharge chamber below said retort chamber, valve means controlling the flow of material from said supply chamber to said pretreatment chamber, means for applying and releasing vacuum in said pretreatment chamber, valve means controllin the flow of material into and out of said transfer chamber, means for applying and releasing vacuum in said retort chamber; means for heatin said retort chamber; a condensing chamber in said retort chamber, a vapor passage affording communication between the retort proper and the condensing chamber, means for alternatively heating and cooling said condensing chamber to alternately condense and remelt the magnesium therein; and material-level responsive means in said discharge chamber for controlling certain of the material valves and densing chamber heating and cooling means.

0. An installation for the continuous recovery of metallic magnesium adapted (1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents which will not evolve gaseous products and (2) for the evaporation of magnesium contained in the dust produced by other thermal reduction methods; said installation comprising, in combination, a vertically arranged, gravityfeed, intercommunicating series of air-tight chambers, said chambers including a pretreatment chamber and a subsequent lower retort chamber, a supply chamber above said pretreatment chamber and a transfer chamber in the vertical series between the pretreatment chamber and the retort chamber, and aresidue discharge chamber below said retort chamber, valve means controlling the flow of material from said supply chamber to said pretreatment chamber, means for applyin and releasing vacuum in said pretreatment chamber, valve means controlling the flow or material into and outof said transfer chamber, means for applying and re leasing vacuum in said retort chamber; means for heating said retort chamber; a condensing chamber in said retort chamber, a vapor passage affording communication between the retort proper and the condensing chamber, means for alternatively heating and cooling said condensing chamber to alternately condense and remelt the magnesium therein; a final discharge valve at the bottom of said discharge chamber; material-level responsive means in said supply chamber for controllin certain of the material valves and vacuum supplying and releasing means, material-level responsive means in said transfer chamber for controlling certain of the material valves and vacuum supplying and releasing means; and material-level responsive means in said discharge chamber for controlling certain of the material valves and vacuum supplying and release means, said condenser chamber heatin and cooling means, and said discharge valve.

11. An installation for the continuous recovery of metallic magnesium adapted (1) for the thermal reduction method involving reacting magnesium containing compounds together with reducing agents which will not evolve gaseous products and (2) for the evaporation of magnesium contained in the dust produced by other thermal reduction methods, said installation comprising, in combination, a vertically arranged, gravity-feed, intercommunicating series of airtight chambers, said chambers including the following in the order named in the downward direction: a supply chamber; a pretreatment chamber; a transfer chamber; a retort chamber, including a retort and a condensing chamber, provided with heating and cooling means and a tapping outlet, and a discharge chamber: a material inlet valve for said supply chamber; a material outlet valve for delivery of material from said supply chamber to said pretreatment chamber, a material flow controlling valve between said pretreatment chamber and said transfer chamber and acting as an inlet valve for the transfer chamber, an outlet valve for the transfer chamber controlling flow of material from said transfer chamber to the retort in said retort chamber, and a final material residue discharge valve at the bottom of said discharge chamber; means for applying vacuum to and releasing it acaaaea from said supply chamber; means. for supplying vacuum to. and releasing it: from said pretreatment chamber, means forapplying vacuum to and releasing it from. said transfer chamber, means for supplying inert gas to said transfer;

chamber andreleasing-ittherefrom, means for applying vacuum to and releasing it from said retort. chamber, means. for heating said retort chamber, meansfor supplying inert gas to said retortchamber and: releasing it therefrom; materialr-levelresponsive means in said. supply chamber for. controlling the material inlet and outlet. valves of the supply chamber and the vacuum applying and, releasing means thereof; material-level responsive. means; in said transfer chamber for; controlling thematerial inletand outlet valves. of the-transfer. chamber, the vacuum applying and, releasing means thereof,v and a residual materialelevel responsive means in said discharge chamber for controlling the. material inlet and outlet valves of. the transfer chamber, the, vacuum applying and releasing meansfor both the transfer. chamber. and the retort chamber, the inert gas supplying and releasingmeans. for the transfer and. retort chambars, the condenser heating and cooling means, and the final residue discharge valve.

1-2. Aninstallation for. the. continuous recovery of metallic magnesium adapted (1) for the thermal reduction. method involving reacting magnesium containing compounds. together with reducing agents which will not evolve gaseous products and (2). for the evaporation of magnesium contained in. the. dust produced by other thermal reduction methods, said installation comprising, in combination, a vertically arranged, gravityfeed, intercommunicating series. of. air-- tight chambers, saidchambers including the following in the order named in thedownward direction: a supply chamber; a pretreatment chamber including av lower cooling. zone and a discharge. regulator; a transfer chamber; a retort chamber, including a. retort anda condensing chamber, provided. with. heating and cooling means. and a tapping: outlet, said retort chamber also including a discharge regulating means; and a dischargev chamber: a material. inlet valve for said. supply chamber; a. material outlet-valve for delivery of material from said supply chamber to said pretreatment chamber, a material flow controlling valve-between said pretreatment chamber and, said. transfer chamber and. acting as an inlet valve. for the. transfer chamber, an outlet valve for the transfer chamber controlling flow of material. from said transfer chamber to. theretort. in: said, retortchamber, and a; final material. residue. discharge valve.- at the bottom 116 of said discharge chamber; means for: applying vacuum to: and releasing it. from said supply chamber; means for supplying vacuum. to and releasing it from said pretreatment chamber, means for. supplyingcooling means to said cooling zone, means for applying. vacuum to and releasing it from said transfer chamber, means for supplying inert gas to said transfer chamber and releasing it therefrom, means for applying vacuum to. and releasing, it from said. retort chamber, means for supplying inert gas. to; said retortchamber and releasing it therefrom; means for heating said retort chamber; high. and low material-level responsive means in said supply chamber for. controlling. the. material. inlet; and; outlet: valves of: the supply chamber andthe. vacuumapplying and releasing means thereof; high and low material-level. responsive means. in said transfer chamber for. controlling the material inlet and outlet valves of. the transfer chamber, thevacuum applying and releasing means thereof, and the discharge regulating means therein; and a high residual. material-level responsive means in said discharge. chamber for controlling the material inlet. and outlet valves of the transfer chamber, the. vacuum applying and releasing means for both the transfer chamber and the retort chamber, the inert gas supplying and re leasing means: for the transfer and retort chambers, thedischarge regulator for the retort cham. ber, the condenser heating and cooling means, and the final residue discharge valve.

JOSEF'INE MARIA HANSGIRG; Administratriw of the estate of Fritz J. Hansgirg,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 951,086 Thomson et a1 Mar. 1, 1910 1,304,425 Weidenthal May 20, 1919 1,549,597 Miller Aug. 11,1925 2,011,288 Kemmer Aug. 13, 1935 2,097,689 Erdmann et a1 Nov. 2, 1937 2,159,910 Seligeret al May 23, 1939 2,161,916 Erdmann June 13, 1939 2,195,453 Gardner Apr. 2, 1940 2,304,469 Maier Dec. 8, 1942 2,337,042 Gloss Dec. 21, 1943 2,338,175 Gibson Jan. 4, 1944 2,497,096 Parry Feb. 14, 1950 2,516,474 Melsted June 25, 1950 FOREIGN PATENTS Number Country Date 907,136 France June 11, 1945' 

4. IN AN APPARATUS OF THE CLASS DESCRIBED, A RETORT CHAMBER, A TUBULAR RETORT DISPOSED IN SAID CHAMBER WITH ITS WALLS SPACED FROM THE WALLS OF THE CHAMBER, MEANS FOR CHARGING MATERIAL INTO AND DISCHARGING IT FROM SAID RETORT, SAID RETORT BEING IN THE FORM OF A SUBSTANTIALLY CYLINGRICAL CAGE AND COMPRISING A COMPLETELY ANNULAR SERIES OF PARALLEL VERTICAL RODS, SAID RODS BEING OF ELECTRICALLY RESISTANT MATERIAL AND BEING SPACED APART A SLIGHT DISTANCE TO PROVIDE OPENINGS THROUGH WHICH SAID RAW MATERIAL MAY NOT PASS BUT THROUGH WHICH VAPORS EVOLVED FROMT HE MATERIAL MAY PASS TO THE SPACE BETWEEN THE WALLS OF SAID 